This report is one element of a co-operative agreement between NHTSA and UMTRI entitle Intelligent Cruise Control (ICC) Field Operational Test (FOT). It addresses the operation and a serial string or dense cluster of passenger cars equipped with a new automotive technology called adaptive cruise control (ACC). The string or cluster conditions are expected to arise commonly on public roadways in the future if ACC reaches high levels of penetration in the vehicle population. This report presents derived from a very limited experimental study of string and cluster operations, as enabled by the availability of vehicles equipped with ACC systems after their use in an extensive field operational test (see Volumes I and II of this report, see ST 991807). The experiments involved a naturalistic traffic setting but a contrived procedure for inserting a dense grouping of ACC-equipped vehicles within the traffic stream. This work also served as a probing attempt to evaluate the impact of multiple ACC-equipped vehicles on such general issues as safety, traffic flow, and interference with unequipped vehicles. Conclusions from this activity pertain both to the issue of test methodology and to the long-term impacts of ACC on traffic operations. (A)
Abstract